/*
  ==============================================================================

   This file is part of the JUCE 7 technical preview.
   Copyright (c) 2022 - Raw Material Software Limited

   You may use this code under the terms of the GPL v3
   (see www.gnu.org/licenses).

   For the technical preview this file cannot be licensed commercially.

   JUCE IS PROVIDED "AS IS" WITHOUT ANY WARRANTY, AND ALL WARRANTIES, WHETHER
   EXPRESSED OR IMPLIED, INCLUDING MERCHANTABILITY AND FITNESS FOR PURPOSE, ARE
   DISCLAIMED.

  ==============================================================================
*/

namespace juce
{

extern ComponentPeer* createNonRepaintingEmbeddedWindowsPeer (Component&, void* parent);

//==============================================================================
class OpenGLContext::NativeContext  : private ComponentPeer::ScaleFactorListener
{
public:
    NativeContext (Component& component,
                   const OpenGLPixelFormat& pixelFormat,
                   void* contextToShareWithIn,
                   bool /*useMultisampling*/,
                   OpenGLVersion version)
    {
        dummyComponent.reset (new DummyComponent (*this));
        createNativeWindow (component);

        PIXELFORMATDESCRIPTOR pfd;
        initialisePixelFormatDescriptor (pfd, pixelFormat);

        auto pixFormat = ChoosePixelFormat (dc, &pfd);

        if (pixFormat != 0)
            SetPixelFormat (dc, pixFormat, &pfd);

        initialiseWGLExtensions (dc);
        renderContext = createRenderContext (version, dc);

        if (renderContext != nullptr)
        {
            makeActive();

            auto wglFormat = wglChoosePixelFormatExtension (pixelFormat);
            deactivateCurrentContext();

            if (wglFormat != pixFormat && wglFormat != 0)
            {
                // can't change the pixel format of a window, so need to delete the
                // old one and create a new one..
                releaseDC();
                nativeWindow = nullptr;
                createNativeWindow (component);

                if (SetPixelFormat (dc, wglFormat, &pfd))
                {
                    deleteRenderContext();
                    renderContext = createRenderContext (version, dc);
                }
            }

            if (contextToShareWithIn != nullptr)
                wglShareLists ((HGLRC) contextToShareWithIn, renderContext);

            component.getTopLevelComponent()->repaint();
            component.repaint();
        }
    }

    ~NativeContext() override
    {
        deleteRenderContext();
        releaseDC();

        if (safeComponent != nullptr)
            if (auto* peer = safeComponent->getTopLevelComponent()->getPeer())
                peer->removeScaleFactorListener (this);
    }

    bool initialiseOnRenderThread (OpenGLContext& c)
    {
        threadAwarenessSetter = std::make_unique<ScopedThreadDPIAwarenessSetter> (nativeWindow->getNativeHandle());
        context = &c;
        return true;
    }

    void shutdownOnRenderThread()
    {
        deactivateCurrentContext();
        context = nullptr;
        threadAwarenessSetter = nullptr;
    }

    static void deactivateCurrentContext()  { wglMakeCurrent (nullptr, nullptr); }
    bool makeActive() const noexcept        { return isActive() || wglMakeCurrent (dc, renderContext) != FALSE; }
    bool isActive() const noexcept          { return wglGetCurrentContext() == renderContext; }
    void swapBuffers() const noexcept       { SwapBuffers (dc); }

    bool setSwapInterval (int numFramesPerSwap)
    {
        jassert (isActive()); // this can only be called when the context is active..
        return wglSwapIntervalEXT != nullptr && wglSwapIntervalEXT (numFramesPerSwap) != FALSE;
    }

    int getSwapInterval() const
    {
        jassert (isActive()); // this can only be called when the context is active..
        return wglGetSwapIntervalEXT != nullptr ? wglGetSwapIntervalEXT() : 0;
    }

    void updateWindowPosition (Rectangle<int> bounds)
    {
        if (nativeWindow != nullptr)
        {
            if (! approximatelyEqual (nativeScaleFactor, 1.0))
                bounds = (bounds.toDouble() * nativeScaleFactor).toNearestInt();

            SetWindowPos ((HWND) nativeWindow->getNativeHandle(), nullptr,
                          bounds.getX(), bounds.getY(), bounds.getWidth(), bounds.getHeight(),
                          SWP_NOACTIVATE | SWP_NOZORDER | SWP_NOOWNERZORDER);
        }
    }

    bool createdOk() const noexcept                 { return getRawContext() != nullptr; }
    void* getRawContext() const noexcept            { return renderContext; }
    unsigned int getFrameBufferID() const noexcept  { return 0; }

    void triggerRepaint()
    {
        if (context != nullptr)
            context->triggerRepaint();
    }

    struct Locker { Locker (NativeContext&) {} };

    HWND getNativeHandle()
    {
        if (nativeWindow != nullptr)
            return (HWND) nativeWindow->getNativeHandle();

        return nullptr;
    }

private:
    //==============================================================================
    static void initialiseWGLExtensions (HDC dcIn)
    {
        static bool initialised = false;

        if (initialised)
            return;

        initialised = true;

        const auto dummyContext = wglCreateContext (dcIn);
        wglMakeCurrent (dcIn, dummyContext);

        #define JUCE_INIT_WGL_FUNCTION(name)    name = (type_ ## name) OpenGLHelpers::getExtensionFunction (#name);
        JUCE_INIT_WGL_FUNCTION (wglChoosePixelFormatARB)
        JUCE_INIT_WGL_FUNCTION (wglSwapIntervalEXT)
        JUCE_INIT_WGL_FUNCTION (wglGetSwapIntervalEXT)
        JUCE_INIT_WGL_FUNCTION (wglCreateContextAttribsARB)
        #undef JUCE_INIT_WGL_FUNCTION

        wglMakeCurrent (nullptr, nullptr);
        wglDeleteContext (dummyContext);
    }

    static void initialisePixelFormatDescriptor (PIXELFORMATDESCRIPTOR& pfd, const OpenGLPixelFormat& pixelFormat)
    {
        zerostruct (pfd);
        pfd.nSize           = sizeof (pfd);
        pfd.nVersion        = 1;
        pfd.dwFlags         = PFD_SUPPORT_OPENGL | PFD_DRAW_TO_WINDOW | PFD_DOUBLEBUFFER;
        pfd.iPixelType      = PFD_TYPE_RGBA;
        pfd.iLayerType      = PFD_MAIN_PLANE;
        pfd.cColorBits      = (BYTE) (pixelFormat.redBits + pixelFormat.greenBits + pixelFormat.blueBits);
        pfd.cRedBits        = (BYTE) pixelFormat.redBits;
        pfd.cGreenBits      = (BYTE) pixelFormat.greenBits;
        pfd.cBlueBits       = (BYTE) pixelFormat.blueBits;
        pfd.cAlphaBits      = (BYTE) pixelFormat.alphaBits;
        pfd.cDepthBits      = (BYTE) pixelFormat.depthBufferBits;
        pfd.cStencilBits    = (BYTE) pixelFormat.stencilBufferBits;
        pfd.cAccumBits      = (BYTE) (pixelFormat.accumulationBufferRedBits + pixelFormat.accumulationBufferGreenBits
                                        + pixelFormat.accumulationBufferBlueBits + pixelFormat.accumulationBufferAlphaBits);
        pfd.cAccumRedBits   = (BYTE) pixelFormat.accumulationBufferRedBits;
        pfd.cAccumGreenBits = (BYTE) pixelFormat.accumulationBufferGreenBits;
        pfd.cAccumBlueBits  = (BYTE) pixelFormat.accumulationBufferBlueBits;
        pfd.cAccumAlphaBits = (BYTE) pixelFormat.accumulationBufferAlphaBits;
    }

    static HGLRC createRenderContext (OpenGLVersion version, HDC dcIn)
    {
        if (version >= openGL3_2 && wglCreateContextAttribsARB != nullptr)
        {
            const int attribs[] =
            {
                WGL_CONTEXT_MAJOR_VERSION_ARB, 3,
                WGL_CONTEXT_MINOR_VERSION_ARB, 2,
                WGL_CONTEXT_PROFILE_MASK_ARB,  WGL_CONTEXT_CORE_PROFILE_BIT_ARB,
                0
            };

            const auto c = wglCreateContextAttribsARB (dcIn, nullptr, attribs);

            if (c != nullptr)
                return c;
        }

        return wglCreateContext (dcIn);
    }

    //==============================================================================
    struct DummyComponent  : public Component
    {
        DummyComponent (NativeContext& c) : context (c) {}

        // The windowing code will call this when a paint callback happens
        void handleCommandMessage (int) override   { context.triggerRepaint(); }

        NativeContext& context;
    };

    //==============================================================================
    void nativeScaleFactorChanged (double newScaleFactor) override
    {
        if (approximatelyEqual (newScaleFactor, nativeScaleFactor)
            || safeComponent == nullptr)
            return;

        if (auto* peer = safeComponent->getTopLevelComponent()->getPeer())
        {
            nativeScaleFactor = newScaleFactor;
            updateWindowPosition (peer->getAreaCoveredBy (*safeComponent));
        }
    }

    void createNativeWindow (Component& component)
    {
        auto* topComp = component.getTopLevelComponent();

        {
            auto* parentHWND = topComp->getWindowHandle();

            ScopedThreadDPIAwarenessSetter setter { parentHWND };
            nativeWindow.reset (createNonRepaintingEmbeddedWindowsPeer (*dummyComponent, parentHWND));
        }

        if (auto* peer = topComp->getPeer())
        {
            safeComponent = Component::SafePointer<Component> (&component);

            nativeScaleFactor = peer->getPlatformScaleFactor();
            updateWindowPosition (peer->getAreaCoveredBy (component));
            peer->addScaleFactorListener (this);
        }

        nativeWindow->setVisible (true);
        dc = GetDC ((HWND) nativeWindow->getNativeHandle());
    }

    void deleteRenderContext()
    {
        if (renderContext != nullptr)
        {
            wglDeleteContext (renderContext);
            renderContext = nullptr;
        }
    }

    void releaseDC()
    {
        ReleaseDC ((HWND) nativeWindow->getNativeHandle(), dc);
    }

    int wglChoosePixelFormatExtension (const OpenGLPixelFormat& pixelFormat) const
    {
        int format = 0;

        if (wglChoosePixelFormatARB != nullptr)
        {
            int atts[64];
            int n = 0;

            atts[n++] = WGL_DRAW_TO_WINDOW_ARB;   atts[n++] = GL_TRUE;
            atts[n++] = WGL_SUPPORT_OPENGL_ARB;   atts[n++] = GL_TRUE;
            atts[n++] = WGL_DOUBLE_BUFFER_ARB;    atts[n++] = GL_TRUE;
            atts[n++] = WGL_PIXEL_TYPE_ARB;       atts[n++] = WGL_TYPE_RGBA_ARB;
            atts[n++] = WGL_ACCELERATION_ARB;
            atts[n++] = WGL_FULL_ACCELERATION_ARB;

            atts[n++] = WGL_COLOR_BITS_ARB;  atts[n++] = pixelFormat.redBits + pixelFormat.greenBits + pixelFormat.blueBits;
            atts[n++] = WGL_RED_BITS_ARB;    atts[n++] = pixelFormat.redBits;
            atts[n++] = WGL_GREEN_BITS_ARB;  atts[n++] = pixelFormat.greenBits;
            atts[n++] = WGL_BLUE_BITS_ARB;   atts[n++] = pixelFormat.blueBits;
            atts[n++] = WGL_ALPHA_BITS_ARB;  atts[n++] = pixelFormat.alphaBits;
            atts[n++] = WGL_DEPTH_BITS_ARB;  atts[n++] = pixelFormat.depthBufferBits;

            atts[n++] = WGL_STENCIL_BITS_ARB;       atts[n++] = pixelFormat.stencilBufferBits;
            atts[n++] = WGL_ACCUM_RED_BITS_ARB;     atts[n++] = pixelFormat.accumulationBufferRedBits;
            atts[n++] = WGL_ACCUM_GREEN_BITS_ARB;   atts[n++] = pixelFormat.accumulationBufferGreenBits;
            atts[n++] = WGL_ACCUM_BLUE_BITS_ARB;    atts[n++] = pixelFormat.accumulationBufferBlueBits;
            atts[n++] = WGL_ACCUM_ALPHA_BITS_ARB;   atts[n++] = pixelFormat.accumulationBufferAlphaBits;

            if (pixelFormat.multisamplingLevel > 0
                  && OpenGLHelpers::isExtensionSupported ("GL_ARB_multisample"))
            {
                atts[n++] = WGL_SAMPLE_BUFFERS_ARB;
                atts[n++] = 1;
                atts[n++] = WGL_SAMPLES_ARB;
                atts[n++] = pixelFormat.multisamplingLevel;
            }

            atts[n++] = 0;
            jassert (n <= numElementsInArray (atts));

            UINT formatsCount = 0;
            wglChoosePixelFormatARB (dc, atts, nullptr, 1, &format, &formatsCount);
        }

        return format;
    }

    //==============================================================================
    #define JUCE_DECLARE_WGL_EXTENSION_FUNCTION(name, returnType, params) \
        typedef returnType (__stdcall *type_ ## name) params; static type_ ## name name;

    JUCE_DECLARE_WGL_EXTENSION_FUNCTION (wglChoosePixelFormatARB,    BOOL,  (HDC, const int*, const FLOAT*, UINT, int*, UINT*))
    JUCE_DECLARE_WGL_EXTENSION_FUNCTION (wglSwapIntervalEXT,         BOOL,  (int))
    JUCE_DECLARE_WGL_EXTENSION_FUNCTION (wglGetSwapIntervalEXT,      int,   ())
    JUCE_DECLARE_WGL_EXTENSION_FUNCTION (wglCreateContextAttribsARB, HGLRC, (HDC, HGLRC, const int*))
    #undef JUCE_DECLARE_WGL_EXTENSION_FUNCTION

    //==============================================================================
    std::unique_ptr<DummyComponent> dummyComponent;
    std::unique_ptr<ComponentPeer> nativeWindow;
    std::unique_ptr<ScopedThreadDPIAwarenessSetter> threadAwarenessSetter;
    Component::SafePointer<Component> safeComponent;
    HGLRC renderContext;
    HDC dc;
    OpenGLContext* context = nullptr;
    double nativeScaleFactor = 1.0;

    //==============================================================================
    JUCE_DECLARE_NON_COPYABLE_WITH_LEAK_DETECTOR (NativeContext)
};


//==============================================================================
bool OpenGLHelpers::isContextActive()
{
    return wglGetCurrentContext() != nullptr;
}

} // namespace juce